Synthesis,static, and dynamic light scattering studies of soluble aromatic polyamide

Aromatic polyamide was synthesized via condensation polymerization of 4‐aminophenyl sulfone (APS) with isophthaloyl chloride (IPC) using N,N‐dimethyl acetamide (DMAc) as a solvent under anhydrous conditions. The purified aramid was studied by laser light scattering (LLS) in dimethyl sulfoxide (DMSO), a thermodynamically good solvent at 20°C. Static and dynamic light scattering studies permitted to determine the weight average molecular weight , radius of gyration , second virial coefficient A₂, the hydrodynamic radius R_H, and the diffusion coefficient D. Light scattering experiments were conducted at five concentrations ranging from 0.27 to 2.5 g/L. LLS measurement is also a very useful technique to study the aggregation or association in a polymer system as long as the large “clusters” are reasonably stable in time. The intensity autocorrelation function obtained on the quasi‐elastically scattered light showed a simple diffusive relaxation mode. The ratio of radius of gyration to the hydrodynamic radius, i.e. ～ 1.3 indicates that the polyamide chain has coil conformation in DMSO at 20°C. Copyright © 2008 John Wiley & Sons, Ltd.     

Novel Substituted Imidazo[2,1‐b][1,3,4]Thiadiazole Derivatives: Synthesis,Characterization, Molecular Docking Study,and Investigation of Their In Vitro Antifungal Activities

In this study, a new series of substituted imidazo[2,1‐b][1,3,4]thiadiazole derivatives were synthesized. To this end, first 2‐amino‐1,3,4‐thiadiazole derivatives (compounds 2a and 2b ), the starting materials, were synthesized with high yields (82% and 79%, respectively). Then imidazo[2,1‐b][1,3,4]thiadiazole derivatives ( 4 – 16 ), the target compounds, were synthesized from reactions of 2‐amino‐1,3,4‐thiadiazole derivatives ( 2a and 2b ) with 2‐bromoacetophenone derivatives ( 3a – 3i ) (in yields of 52% to 71%). All of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR, Fourier transform infrared, elemental analysis, mass spectroscopy, and X‐ray diffraction analysis (compounds 4 – 12 , 14 , and 15 ) techniques. In vitro antifungal activity tests were performed for all of the synthesized compounds. Inhibition zones, percentage of inhibition, minimum fungicidal activity, minimum inhibitory concentration, and lethal dose values of the target compounds were determined against some plant pathogens. According to the results of the biological activity tests, all of the synthesized compounds showed moderate to high levels of antifungal activity. Theoretical calculations were performed to support the experimental results. The geometric parameters of selected compounds ( 5 , 6 , and 8 ) were optimized using the density functional theory B3LYP/6‐31G(d) method in the Gaussian 09W package program, and the frontier molecular orbitals (highest occupied molecular orbital–lowest unoccupied molecular orbital) were calculated theoretically. Finally, molecular docking studies were performed for antifungal activity studies of the selected compounds and to determine whether or not these compounds could be inhibitor agents for the 2RKV protein structure.     

Berberine as a Potential Anticancer Agent: A Comprehensive Review

Berberine (BBR), a potential bioactive agent, has remarkable health benefits. A substantial amount of research has been conducted to date to establish the anticancer potential of BBR. The present review consolidates salient information concerning the promising anticancer activity of this compound. The therapeutic efficacy of BBR has been reported in several studies regarding colon, breast, pancreatic, liver, oral, bone, cutaneous, prostate, intestine, and thyroid cancers. BBR prevents cancer cell proliferation by inducing apoptosis and controlling the cell cycle as well as autophagy. BBR also hinders tumor cell invasion and metastasis by down-regulating metastasis-related proteins. Moreover, BBR is also beneficial in the early stages of cancer development by lowering epithelial–mesenchymal transition protein expression. Despite its significance as a potentially promising drug candidate, there are currently no pure berberine preparations approved to treat specific ailments. Hence, this review highlights our current comprehensive knowledge of sources, extraction methods, pharmacokinetic, and pharmacodynamic profiles of berberine, as well as the proposed mechanisms of action associated with its anticancer potential. The information presented here will help provide a baseline for researchers, scientists, and drug developers regarding the use of berberine as a promising candidate in treating different types of cancers.     

On the construction of tolerance interval for two‐way random effect model

Statistical tolerance limits have been widely applied in the area of applied statistics, particularly in engineering, manufacturing, reliability, and quality control processes in industries. This article attempts to generalize the one‐way model into the balanced two‐way random effect model and suggest various alternative tolerance limits as a special case of the new complexity. © 2000 John Wiley & Sons, Inc. Complexity 5: 61‐64, 2000     

Facile Access to AgOCF3 and Its New Applications as a Reservoir for OCF2 for the Direct Synthesis of N−CF3, Aryl or Alkyl Carbamoyl Fluorides

The development of innovative fluorination strategies is greatly dependent also on the availability, safety and practicability of available fluorinating reagents. We herein show a straightforward and quantitative strategy for the preparation of valuable AgOCF₃ at room temperature and showcase its performance in trifluoromethoxylations or as reservoir for O=CF₂. This enabled the direct, practical and safe synthesis of valuable N-alkyl/aryl and N−CF₃ carbamoyl fluorides from secondary amines and isothiocyanides, respectively. Our mechanistic data indicate that AgOCF₃ does not liberate O=CF₂ until it is activated by a nucleophilic co-reagent, reinforcing the stability of the salt under our new preparation strategy.     

DFT STUDY OF THE STRUCTURE,CONFORMATIONAL PROFILE AND THE VIBRATIONAL ANALYSIS OF 2-FURANCARBOTHIALDEHYDE AND 3-FURANCARBOTHIALDEHYDE

Journal of Structural Chemistry - The aim of this work is to study theoretically the geometrical structure, conformational preference, and vibrational properties of rotational isomers of 2- and...     

Synthesis and single crystal X‐ray determination of the Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene

The reaction of acetylferrocene [Fe(η‐C₅H₅)(η‐C₅H₄COCH₃)] (1) with (2‐isopropyl‐5‐methylphenoxy) acetic acid hydrazide [CH₃C₆H₃CH(CH₃)₂OCH₂CONHNH₂] (2) in refluxing ethanol gives the stable light‐orange–brown Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene, [CH₃C₆H₃CH(CH₃)₂OCH₂CONHN?C(CH₃)Fe(η‐C₅H₅)(η‐C₅H₄)] (3). Complex 3 has been characterized by elemental analysis, IR, ¹H NMR and single crystal X‐ray diffraction study. It crystallizes in the monoclinic space group P2₁/n, with a = 9.6965(15), b = 7.4991(12), c = 29.698(7) Å, β = 99.010(13) °, V = 2132.8(7) ų, D_calc = 1.346 Mg m^?3; absorption coefficient, 0.729 mm^?1. The crystal structure clearly shows the characteristic [N? H···O] hydrogen bonding between the two adjacent molecules of 3. This acts as a bidentale ligand, which, on treatment with [Ru(CO)₂Cl₂] _n, gives a stable bimetallic yellow–orange complex (4). Copyright © 2002 John Wiley & Sons, Ltd.     

Reclamation of Used Engine Oil

Used lubricating oil from vehicles was treated with various types of chemicals to be regenerated. It was found that used lubricating oil could be reclaimed with sulphuric acid, sodium hydroxide, sodium phosphate, ammonium sulphate and rosin. Viscosity and pour point of the reclaimed lubricating oil were improved with the additive methyl methacrylate. The reclaimed lubricating oil was characterized by four‐ball ma chine and it was found that wear scar diameter (WSD) has greatly been de creased with the reclamation. The results of atomic absorption spectrophotometer also show that wear metals have also been de creased to an appreciable amount in there claimed lubricating oil.     

Role of substrate temperature on structure and magnetization of Cr-implanted GaN thin film

Chromium ions implantation was performed into metal–organic chemical vapor deposition grown GaN thin film of thickness about 2 µm at 5 × 10¹⁶ cm^?2 fluence. Implantation was performed at various substrate temperatures (RT, 250, 350 °C). Rapid thermal annealing was employed at 900 °C to remove implantation-induced damages as well as for activation of dopant. Structural study was performed by Rutherford backscattering and channeling spectrometry and high-resolution X-ray diffraction. To confirm magnetic properties at room temperature, hysteresis loops were obtained using alternating gradient magneto-meter. Well-defined hysteresis loops were achieved at 300 K in implanted and annealed samples. Temperature-dependent magnetization indicated magnetic moment at 5 K and retain up to 380 K.